RTD Probe Vibration Resistance via Extended Sheath
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Solution Overview
Problem
Resistance thermal devices (RTDs) in thermal probes are susceptible to damage from vibrations, especially when used in process fluid flow measurements, as they are typically positioned near the end of the sheath, leading to increased susceptibility to vibration-induced damage.
Innovation Solution
Extending the length of the sheath away from the RTD element to position it at a location of minimum deformation during vibrations, thereby reducing the impact of vibrations on the RTD, and optionally using biasing elements around the external diameter of the sheath to further stabilize it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the RTD element is positioned near the end of the sheath to ensure effective thermal contact, then thermal measurement accuracy is improved, but vibration resistance deteriorates
Solution Approach 1:
The patent introduces an intermediary structure (the extended sheath portion) between the RTD element and the vibration source. By extending the sheath beyond the RTD element's position, the sheath acts as a mechanical buffer that isolates the RTD from vibrations while maintaining thermal contact through the sheath material itself, thus resolving the contradiction between measurement accuracy and vibration resistance
2Use of energy by moving object
If the RTD element is positioned near the end of the sheath to reduce thermal resistance, then thermal contact efficiency is improved, but susceptibility to vibration-induced damage increases
Solution Approach 1:
The extended sheath serves as a mediator that decouples the thermal conduction path from the mechanical vibration path. The sheath material conducts heat effectively to the RTD element while its extended length provides mechanical isolation from vibrations, thereby maintaining thermal efficiency while reducing vibration-induced damage
3Reliability
If the sheath length is extended away from the RTD element to provide vibration resistance, then device complexity increases, but vibration resistance is improved
Solution Approach 1:
The sheath is segmented into functional zones: a measurement zone where the RTD element contacts the process medium, and an extended isolation zone that provides vibration resistance. This segmentation allows each portion to fulfill its specific function without increasing overall device complexity, as the extension is a simple geometric modification rather than a complex structural addition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The extended sheath design significantly improves vibration resistance of RTD probe assemblies, reducing the risk of damage from vibrations without altering the sensor element's location, and additional stabilization elements help minimize movement within measurement structures, enhancing the RTD's endurance under various vibration frequencies.
Implementation Method 1
an RTD element having an electrical resistance that varies with temperature
Implementation Method 2
spaced from a distal end of the sheath by a distance selected to provide vibration resistance to the RTD element
Data Source
AI summary
A thermal probe assembly includes an RTD element having an electrical resistance that varies with temperature. A plurality of leadwires is operably coupled to the RTD element. The RTD element is disposed within a sheath and spaced from a distal end of the sheath by a distance selected to provide vibration resistance to the RTD element.